When we encounter a shadow, we often infer the illumination and the 3D object that produced it. While a given 2D shadow corresponds to many possible combinations of object and illumination, context and our prior experience frequently allow us to infer the nature of the illuminated object. In Hidden Dimensions, similar shadows cast by varied 3D structures allow the visitor to experience the variability in form and illumination that can result in a given 2D image. This is a specific example of the ill-posed inverse problem in visual perception: how does the brain create a consistent experience of the world from light information that has many possible interpretations?